Moisture by Capillarity is one of the most frequent types of humidity.
This type of moisture occurs when moisture is rising through the capillaries or pores of the walls.
The origin of the humidity is the earth on which houses are built that gets wet when it rains. If in the subsoil there is water betas then the earth will remain wet permanently.
The bricks capillaries or cement of all houses absorb moisture naturally as a sponge absorbs water, but not all houses have moisture.